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# Control of Resonance Amplitude for Josephson Logic

IP.com Disclosure Number: IPCOM000052450D
Original Publication Date: 1981-Jun-01
Included in the Prior Art Database: 2005-Feb-11
Document File: 2 page(s) / 40K

IBM

## Related People

Gheewala, TR: AUTHOR

## Abstract

Non-latching Josephson logic circuits are designed in which the output current is switched on or off by controlling the resonance amplitude of an interferometer. These circuits will work with high impedance terminated transmission lines.

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Control of Resonance Amplitude for Josephson Logic

Non-latching Josephson logic circuits are designed in which the output current is switched on or off by controlling the resonance amplitude of an interferometer. These circuits will work with high impedance terminated transmission lines.

For low Q interferometers, the resonance amplitude depends on the control current I(c), as given by the resonance step I(s)/I(mo) = A sin/2/ Pi LI(c) over Chi
(0). where L is the magnetically coupled inductance of the interferometer and A is the maximum amplitude of the resonance step when LI(c)=Phi(0)/2. By a proper choice of L's I(0)'s and the damping resistors, the maximum resonance amplitude A can be made as large as 0.6.

The circuit of Fig. 1 shows a non-latching inverter driving a high impedance load R(L). The current-voltage (I-V) curve in Fig. 2 shows the small output current I when the control current is on. When the control current is removed, the resonance amplitude decreases to that shown by the dashed line in Fig. 2. The output current increases to I(L1). Typically, for I = 50 microamps, the load resistor R(L) = 12 ohms will intersect the resonance bump curve at its peak. The interferometer 10 can be asymmetric so that the leakage current in the "0" state, I(LO), will be just enough to cancel the self-field of the asymmetric interferometer
10. The margins on this inverter are excellent because the gate current I will be a DC current. When two control currents A and B of opposing polarities are applied to interferometer 10, the function A B is obtained.

A non-latching NOR gate is shown in Fig. 3. This gate is comprised of series-conne...